To operate efficiently and with minimal light waste, many projectors require a light beam that has a balance of three colors for producing an adequately large colour gamut. However, many traditional light sources produce a light beam that deviates from such an optimal balance. As a result, some portions of the generated light beam may not be usable to generate the projected image; these portions would constitute wasted power and contribute to unwanted heat. Additional power can be used to deal with the unwanted heat (e.g. in the form of active cooling components and the like), which leads to an overall degradation of the energy efficiency of such systems.
For example, in the case of a light source comprising a yellow phosphor excited by a blue laser, the light beam generated by the yellow phosphor may have an excess of yellow and green, and a deficiency of red. While other emitters, such as quantum dots can emit red light, these quantum dots typically operate at incident power levels lower than required for many projection applications.